MONMOUTH, Ore. - A farmer looking for a lost cow found a fully operational pre-World War II artillery shell backed with 15 pounds of TNT, the Polk County Sheriff's Office said.

The farmer reported finding the shell 500 yards off Elkins Road, just south of Monmouth, in an area that used to be part of the artillery ranges for Camp Adair.

"The Sheriff's Office use to respond to two or three of these calls a year back in the 1970s," Polk County Sheriff Bob Wolfe said.

But the farmer's find last Friday was the first in a long time, Wolfe said.

Deputies secured the area. The Salem Bomb Squad and the United States Air Force Explosive Ordinance Disposal unit from Portland responded to the scene and took over the disposal process for the shell.

The EOD unit decided to wait until Saturday morning to dispose of the shell for safety reasons. Sheriff's office personnel guarded the area overnight, and bomb disposal crews returned to the scene Saturday and disposed of the shell.

Military personnel on scene identified the shell as a pre-World War II artillery shell with a range of 12 miles.

The shell was fully operational with a high explosive tip attached.

The shell measured over two feet in length and weighed approximately 113 pounds. The high explosive tip contained approximately 15 pounds of TNT.